public class SolutionInterview1_1 {
    public boolean isUnique(String astr) {
        boolean[] f=new boolean[26];
        for (char c : astr.toCharArray()) {
            if (f[c-'a']){
                return false;
            }
            f[c-'a']=true;
        }
        return true;
    }

    public static void main(String[] args) {
        System.out.println(new SolutionInterview1_1().isUnique("leetcode"));
    }
}
